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WebSocket vs SSE (Server-Sent Events)



  • Definition: A computer communications protocol, providing full-duplex communication channels over a single TCP connection.
  • Usage: Typically used in applications that require real-time, bidirectional communication, like chat applications, gaming, and live sports updates.

SSE (Server-Sent Events)

  • Definition: A standard allowing a web page to get updates from a server.
  • Usage: Primarily used for one-way communication from server to client, such as live blogs, news feeds, or social media updates.
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Key Comparisons

  1. Communication Flow

    • WebSocket: Allows two-way communication (client-server and server-client).
    • SSE: Designed primarily for one-way communication (server-client).
  2. Protocol and Transport

    • WebSocket: Uses the WebSocket protocol (ws:// and wss:// for secure).
    • SSE: Utilizes standard HTTP/HTTPS for data transmission.
  3. Browser Support

    • WebSocket: Supported by all major browsers.
    • SSE: Limited support in some browsers (e.g., not natively supported in Internet Explorer).
  4. Implementation Complexity

    • WebSocket: Slightly more complex to implement due to its own protocol.
    • SSE: Easier to implement, especially on the client side, due to its use of standard HTTP.
  5. Overhead and Performance

    • WebSocket: More overhead for establishing connections, but efficient for frequent, small messages.
    • SSE: Less initial overhead, but less efficient for frequent, bidirectional communication.
  6. Use Cases

    • WebSocket: Ideal for interactive applications requiring real-time data in both directions (e.g., online gaming, collaborative tools).
    • SSE: More suited for applications where the server updates the client in real-time without needing client input (e.g., stock tickers, news feeds).
  7. Network Handling

    • WebSocket: Maintains a persistent connection, which can be more demanding on server resources.
    • SSE: Connections are treated as regular HTTP traffic, which can be more efficient for server resource usage.


  • WebSocket: Best suited for applications requiring full duplex, real-time communication and interactive features.
  • SSE: A good choice for simpler applications where the server needs to update the client in real-time, but client interaction is limited or unidirectional.